Remove empty `case` and `if` replace with body

[wsnyder]

The below is the result of minimizing, for Verilator giving a %q as the only error. (Arbitrary way to look for the display statement still existing):

package uvm_pkg;
  virtual class uvm_report_catcher;
    function string get_id();
    endfunction
  endclass
endpackage
module t;
  import uvm_pkg::*;
  class my_catcher extends uvm_report_catcher;
    virtual function int catch(string msg);
      if (get_id() == "UVMCB_TRC") begin
        case ("Z")
          "A": $display("bad format %q");
          "B": $display("format");
          "C": $display("format");
        endcase
      end
    endfunction
  endclass
endmodule

I think best-case output is:

module t;
  class my_catcher;
    virtual function int catch(string msg);
        $display("bad format %q");
    endfunction
  endclass
endmodule

Please consider

1. try removing case items.
2. try case (x) ign: y becomes y
3. try if (x) y becomes y.
4. try if (x) ign; else y becomes y.

Thanks.